This invention has to do with the modification of well known bag making machines to increase the production capability of such well known bag machines. The "poly" bag making industry is a well developed industry with numerous bag machine styles competing for a share of the market. A typical bag making machine is the FMC Corporation's Model 175W bag making machine which is a bag machine that produces "side weld" poly bags and stacks the completed bags using a "wicketer", as is well known in the art.
The "175W" is equipped with a main drive electric motor that drives a main drive shaft. Moving elements such as draw rolls, seal head and the wicketer are driven by the main drive motor. The draw rolls, which pull a web of film from a supply of film, either a roll of film or a continuously extruded web of film, are driven by a gear and pulley system utilizing a crank and rocker linkage to a segment gear, which utilizes a well known conventional clutch/brake system to connect a reciprocating motion into a reversible one direction rotary motion. The motion produced by this "clutch/brake means" is a harmonic motion that, based on the various gear ratios, will yield a maximum film web acceleration as the film web is drawn through the draw rolls, for any given number of machine cycles, as determined by a single rotation of the main drive shaft. This will be discussed further on in this Specification.
It is desirable to increase bag machine production; however, the aforesaid peak film acceleration has been a limiting factor.
The invention presented herein is an advantage over current production bag machines in that the peak film acceleration for any given machine speed (cycles per minute) has been reduced. This permits the machine to operate at a higher speed, and produce more bags per minute, without exceeding the maximum velocity tolerated by the web. Thus allowing faster machine cycles at the same peak film acceleration.
The advantage of this technology also directly applies to existing "conventionally" driven bag machines similar to the Model 175W mentioned above. Using the invention disclosed herein it is apparent that the technology can be directly applied to the conventional machines, with some serious machine modifications, to enable the prior existing machines to increase their levels of production to those accomplishable by a current production servo draw roll and seal roll drive machine.